Charts for use during subnetting and general base conversions.
Subnetting Chart
(Thanks to David Beach of C.N.M.)
This chart can be created on the fly once you are in the test. To use it, first determine which default class you are working in. If the IP address space given is 192.168. 3.0 /24, then you are in a subnet of a class C. Next, figure out how many hosts you need on your network. Let's say you need 59 hosts. Find the next higher power of two in green, 64. That's a /26 which gives you a magic number of 64 (this is your increment), and a subnet mask of 255.255.255.192. This means your next higher network number will be 192.168.3.0 + 64 = 192.168.3.64. Now that you have the lower and upper limits, you can fill in the first host, last host and broadcast addresses.
Example:
| Network Number | First Host | Last Host | Broadcast |
| 192.168.3.0 | 192.168.3.1 | 192.168.3.62 | 192.168.3.63 |
| 192.168.3.64 |
Chart:
| MASK | 128 | 192 | 224 | 240 | 248 | 252 | 254 | 255 |
| MAGIC | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
| A | /9 | /10 | /11 | /12 | /13 | /14 | /15/ | 16 |
| (hosts) | 8388608 | 4194304 | 2097152 | 1098576 | 524288 | 262144 | 131072 | 65536 |
| B | /17 | /18 | /19 | /20 | /21 | /22 | /23 | /24 |
| (hosts) | 32768 | 16384 | 8192 | 4096 | 2048 | 1024 | 512 | 256 |
| C | /25 | /26 | /27 | /28 | /29 | /30 | /31 | /32 |
| (hosts) | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
(See how to create the above chart on the fly during an exam.)
Subnet mask chart:
| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 255 |
| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 254 |
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 252 |
| 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 248 |
| 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 240 |
| 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 224 |
| 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 192 |
| 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 128 |
Table for converting from
decimal to binary:
| 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 |
| 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
This is easy to remember and makes
it fast to get to the higher powers:
210 = 1024
General purpose chart for converting
between decimal, hex and binary:
| 0 | 0 | 0 | 0 | 0 | 0 |
| 1 | 1 | 0 | 0 | 0 | 1 |
| 2 | 2 | 0 | 0 | 1 | 0 |
| 3 | 3 | 0 | 0 | 1 | 1 |
| 4 | 4 | 0 | 1 | 0 | 0 |
| 5 | 5 | 0 | 1 | 0 | 1 |
| 6 | 6 | 0 | 1 | 1 | 0 |
| 7 | 7 | 0 | 1 | 1 | 1 |
| 8 | 8 | 1 | 0 | 0 | 0 |
| 9 | 9 | 1 | 0 | 0 | 1 |
| 10 | A | 1 | 0 | 1 | 0 |
| 11 | B | 1 | 0 | 1 | 1 |
| 12 | C | 1 | 1 | 0 | 0 |
| 13 | D | 1 | 1 | 0 | 1 |
| 14 | E | 1 | 1 | 1 | 0 |
| 15 | F | 1 | 1 | 1 | 1 |
Count by 4, 8, 16, 32 chart:
| 4 | |||
| 8 | 8 | ||
| 12 | |||
| 16 | 16 | 16 | |
| 20 | |||
| 24 | 24 | ||
| 28 | |||
| 32 | 32 | 32 | 32 |
| 26 | |||
| 40 | 40 | ||
| 44 | |||
| 48 | 48 | 48 | |
| 52 | |||
| 56 | 56 | ||
| 60 | |||
| 64 | 64 | 64 | 64 |
| 68 | |||
| 72 | 72 | ||
| 76 | |||
| 80 | 80 | 80 | |
| 84 | |||
| 88 | 88 | ||
| 92 | |||
| 96 | 96 | 96 | 96 |
| 100 | |||
| 104 | 104 | ||
| 108 | |||
| 112 | 112 | 112 | |
| 116 | |||
| 120 | 120 | ||
| 124 | |||
| 128 | 128 | 128 | 128 |
| 132 | |||
| 136 | 136 | ||
| 140 | |||
| 144 | 144 | 140 | |
| 148 | |||
| 152 | 152 | ||
| 156 | |||
| 160 | 160 | 160 | 160 |
| 164 | |||
| 168 | 168 | ||
| 172 | |||
| 176 | 176 | 176 | |
| 180 | |||
| 184 | 184 | ||
| 188 | |||
| 192 | 192 | 192 | 192 |
| 196 | |||
| 200 | 200 | ||
| 204 | |||
| 208 | 208 | 208 | |
| 212 | |||
| 216 | 216 | ||
| 220 | |||
| 224 | 224 | 224 | 224 |
| 228 | |||
| 232 | 232 | ||
| 236 | |||
| 240 | 240 | 240 | |
| 244 | |||
| 248 | 248 | ||
| 252 | |||
| 256 | 256 | 256 | 256 |